I'm commonly asked what the best age for a rhinoplasty is and the simple answer to that question is, there really is no best age. The age at which one should get a rhinoplasty is whatever age a person is when he or she is most bothered by the appearance of their nose. There is certainly an age where I would not perform a rhinoplasty.
I like to wait until a patient is at least 16 years old before considering rhinoplasty. You want to give the face and the nose an opportunity to grow as much as possible before attempting to change anything about it.
That being said, I'm a Craniofacial surgeon and sometimes we perform surgical procedures on the noses of younger children who have abnormalities that they were born with but when considering a elective cosmetic rhinoplasty, I would certainly be willing to have the discussion with the person once they turn 16 but there is no real set age that is best.